1. Field of the Invention
The present invention is related to a method and a system for displaying 3D images, and more particularly, to a method and a system for displaying 3D images with reduced image interference.
2. Description of the Prior Art
Three-dimensional (3D) display technology provides more vivid visual experiences than traditional two-dimensional (2D) display technology. In general, the stereoscopic image processing involves presenting left-eye images and right-eye images respectively to the left eye and right eye of a viewer. In this way, an illusion of depth is created by simulating normal vision. The visual cortex of the human brain fuses this into perception of a 3D scene or composition.
There are two major types of 3D viewing environments: autostereoscopic 3D display system and glasses-type 3D display system. In autostereoscopic viewing environment, stereoscopic images are directly generated using e-holographic, volumetric, or multi-planar optical devices and can be viewed without additional devices. However, in additional to higher costs, the depth/brightness performance of an autostereoscopic 3D display system is limited and its 3D effect varies with viewer position.
In glasses-type viewing environment, 3D viewing devices, such as polarizing glasses, shutter glasses, or anaglyph glasses are required to create the illusion of stereoscopic images from planer images. Polarizing glasses, widely used in I-MAX movie theaters, include two lenses with different polarization (such as a horizontally polarized left-eye lens and a vertically polarized right-eye lens). A projecting equipment is used for providing images with different polarization, such as horizontally polarized left-eye images and vertically polarized right-eye images). Therefore, a user can view the left-eye images with the left eye and the right-eye images with the right eye. The left-eye images and the right-eye images have identical contents but different depths, thereby capable of simulating stereoscopic effect in human brain.
In a prior art active-matrix organic light-emitting diode (AMOLED) 3D display system using polarizing glasses, a liquid crystal polarizing panel is disposed on an AMOLED display panel: when the AMOLED display panel is displaying left-eye images L, the liquid crystal molecules of the liquid crystal polarizing panel are rotated to a specific angle θL; when the AMOLED display panel is displaying right-eye images R, the liquid crystal molecules of the liquid crystal polarizing panel are rotated to another specific angle θR. Therefore, the left-eye images s L and the right-eye images R may be polarized differently.
FIG. 1 illustrates the operation of the prior 3D display system when the liquid crystal polarizing panel liquid changes the rotation of its crystal molecules according to the scan direction of the AMOLED display panel. Assuming left-eye images L and right-eye images R are alternatively displayed during the sub frame periods F1L F1R F2L F2R . . . , and the prior art liquid crystal polarizing panel begins to switch the angle of its liquid crystal molecules at the start of each sub frame period. In the ideal scenario, the liquid crystal polarizing panel is able to make immediate angle switch of its liquid crystal molecules at the moment the AMOLED display panel switches between left-eye and right-eye images. In the real situation, the rotation of liquid crystal molecules requires a reaction time TLC (represented by the striped region in FIG. 1). For 120 Hz operational frequency, the length of the sub frame periods F1L F1R F2L F2R . . . is 8.3 ms. Thus, the liquid crystal polarizing panel is configured to switch the angle of its liquid crystal molecules every 8.3 ms, but it takes reaction time TLC of about 3 ms before the liquid crystal molecules reach a predetermined angle. In other words, during the reaction time TLC, the user can only view a single left-eye image or a single right-eye image in the ideal scenario, but the user actually views both the left-eye image and the right-eye image in reality. This kind of image crosstalk largely influences the display quality.